Well guys I did it again yesterday. We were tuning the car for the drag strip on sunday, took it out for a trail run on a back road and broke another rocker arm stud. Although I pushed it to around 6900 RPM, the stud actually broke when we were on the way back running about 55 MPH. I heard it and it actually put a nice dent in the valve cover.

The car has 1.5 aluminum Harland Sharp roller rockers with 3/8" studs. My mechanic has suggested that I go to the 7/16" studs. He says he will change them out in exchange for my old rockers. Do you guys think that going to the bigger studs will eleminate this problem? Anyone else ever had this problem? 

The larger studs will help, but, the problem seems to be that there might be too much valve-spring pressure. You might want to have the spring press. tested at the specified height for your cam.
There might also be an alignment problem in the valvetrain.

Or, you got a set of junk studs to begin with.

Joel,

Please explain "an alignment problem in the valvetrain". I have ordered the new roller rockers and 7/16 studs.

rearn2go7238923.779224537

Uh...well...uh.....
When you use roller rockers with guide plates, you must verify that the heads have the large holes where the pushing rods go thru them. I don't know iffin you are using cast iron GM heads or not, but most of them have slotted p-rod holes, which is what keeps the pushrods/rocker arms/valves in line with one another. If you use a roller rockers with guide plates on this type of head, chances are not everything will be lined up properly, and something is gonna bind/break. Usually, it will be the p-rods bending/breaking, or the rockers will run off-center of the valve ends. (I hope I 'splained that well enough for anyone to unnerstand. )

I think you may have a spring problem, tho. Maybe they are too stout for the studs, or they may even be binding(coil bind) at full lift, and that is breaking the studs.
Can you post a pic of the broken studs?
Is it possible that the studs are too short to begin with?
Just throwin out some off the wall ideas....that's all.

Here's a pic of the roller rocker and the broken stud. Both studs that have broken, broke in the "nut". http://www.C3VR.com/member_pages/8301_8400/8356/rocker and stud.jpg 

As for the heads, they are aluminum AFR 190 stage II. I wouldn't know what a guide plate was if I saw it, but I think I remember someone saying that these heads didn't require them with the solid lifters and roller rockers. You tell me.

As for the studs being too short, I have no idea. I was told to order the short ones for the new 7/16 rockers.

Jim , it just looks strange to me that a ( high grade quality steel ???) stud can break while his thread holds in a aluminium block . I think if you should test it , the aluminium thread would be broken long before the bolt itself. A 3/8" , quality 8.8 ( not even very special ) as we use a lot can have a load of 3000 kg , a higher quality as 12.9 up to 5000 kg ! I don't think the aluminium thread would hold that .Ofcourse if there also bending ( alignement ) and/or vibration ( metal fatigue ? ) the most stressed area will be just under the nut .

Can they give the steel quality of there studs ?

My opinion, fer what it ain't worth, is one of two things are wrong wid dis pic.

1) The stud is too short
2) The p-rods am too long

If the studs are too short, or the p-rods too long for the application, the rocker will be too far up on the stud. This will put the rocker up into the threaded area of the stud: not down on the "shoulder" as it should be. When that happens, the rocker has no support, and it tends to flop around, and eventually it breaks the stud from bending back & forth.

The excellent, unfocused pic( ) shows some wear on the threaded end of the stud that the posi-lock threads onto. Looks to me like the rocker is not fully positioned on the shoulder area of the stud. I'll play with the pic, and show you what I mean...news at 10!

Otay...see if this makes any sense...in THIS pic, I have pointed to the area on the stud that the bottom part of the rocker is riding on, as well as the threaded area, where the top part of the rocker is riding. Rollers need to have the entire fulcrum(pivot) part of the rocker supported by the stud, or else there is nothing to keep them from flopping on the upper, threaded part of the stud. There is no support there.
I think you may have studs that are not compatible with rollers. These(yours) look like normal, ball type studs.
I could be wrong , but that's how it appears to me.
Adams' Apple38924.3271412037

Dang Joel, you know I'm no mechanic and now you're saying that i'm ever less of a photographer.  

I talked to American Speed again this morning. We know the pushrods are correct. There is some question about the 3/8 studs since we recently changed the the cam to a higher lift. (.571 intake .577 exhaust) The springs were also chaned so I don't think that's the problem. They seem to think that if I go to the 7/16 studs it will correct the problem.

BTW, they said I should use the "standard" studs, which is the short ones.

Have they(Am. Speed) had this problem before?

I have to agree that going to a larger diameter stud will, at the very least, delay breakage. I still question the compatability of all of the valvetrain components, but...I'd have to go with their recommendations since it is their engine assy.
Keep us up on the progress!

Joel, Gayle at Am. Speed did admit to having had some 3/8 studs break on their engines. As for the compatability of the valvetrain components, it's hard to argue with guys that can get this kind of HP and torque from a small block.

http://www.airflowresearch.com/chevy_dyno.php